The transcription, processing and modification of tRNA will be studied to determine their role in the production of tRNA and thus in the regulation of cellular activities. RNA polymerase and the products are processed by a crude supernatant fraction to effectively produce the tRNAs. Dissection of this system and a characterization of the steps should allow a delineation of their potential regulatory importance. Four projects related to these goals are projected: 1) characterization of the T4 tRNA promoter and the initiation and control of transcription; 2) structural studies of the transcription unit including cloning, sequence determination and electron microscopic examination; 3) modification of T4 tRNA in vitro; 4) Characterization of T4 tRNA transcription in vivo. In addition, a related project will be initiated; 5) the synthesis in vitro of a eukaryotic tRNA.